Pantelleria is a volcanic island located in the Sicilian Channel, about 85 km from the Sicilian coast and only 70 km from the coast of North Africa. With an area of 84 square kilometers, Pantelleria is the largest of Italy's volcanic islands. This volcano owes its existence to the presence of a continental rift ( extended depression where the Earth's crustal thickness thins under the effect of distensional forces) in a geodynamic context characterized by the collision between the Eurasian and African plates. The island represents the summit of a volcanic structure, about 1400m high in total, consisting of lavas and pyroclastic deposits emerging from the surrounding seafloor.
The most recent eruptive activity dates back to 1891 and occurred at an underwater eruptive fracture system about 7 km north of the island (Foerstner Bank).
Currently, only manifestations of widespread thermalism, represented by fumaroles and hot springs, are present on the volcanic island.
The magma that gave rise to the numerous volcanoes that created the island of Pantelleria came to the surface in an area traversed by deep fractures, caused by a spreading movement of the Earth's crust (rift). At the bottom of the Sicilian Channel, over the Pantelleria area, magma came to the surface to form the small island of Linosa and Graham's Bank (Ferdinandea). The island gives its name to a genus of volcanic products, pantellerites, derived from a particularly fluid magma rich in silica and sodium.
The succession above sea level of multiple eruptions over hundreds of thousands of years, the transformations and overlapping of different volcanic cones, which grew and then were demolished over time, make reconstruction of the island's eruptive history problematic.
It is probable that surface eruptions began around 330,000 years ago and built up, with a series of lava flows, a broad, low volcano. Subsequently, large lava flows and pyroclastic deposits were produced from various eruptive centers for 200,000 years, until about 114,000 years ago, when a collapse produced by a large and violent eruption led to the formation of the first of the two almost concentric calderas that characterize the morphology of the island: "La Vecchia," extending 42 km2.
The caldera was later partly filled with pumice and pyroclastic deposits erupted during large explosive eruptions between 106,000 and 79,000 years ago. About 45,000 years ago, a series of very violent explosions led to the formation of a thick pyroclastic deposit that now covers most of the island: the Green Tuff of Pantelleria. This eruptive event generated pyroclastic flows and pumice-fall deposits with a volume of tens of cubic kilometers. During this eruption, the sinking of another zone, internal to the previous one, called the "Caldera dei Cinque Denti" or "Caldera del Monastero," was generated. The final deposits of the Green Tuff and shortly thereafter lava flows emitted in the Monte Gibele area filled much of the caldera.
Volcanic activity continued with several eruptive cycles, probably interspersed with periods of inactivity.
The last eruption in the Pantelleria area occurred in 1891 at an underwater fracture system located about 7 km north of the island. From October 17 to 25 of that year, witnesses observed volcanic bombs emitted during the underwater eruption reach the surface and explode. Surface activity was observed not only from the island, but also from the Sicilian and Tunisian coasts.
Pantelleria is in a quiescent condition, with volcanic manifestations represented mostly by numerous fumaroles and hot springs. The former are concentrated in the central-southern part of the island near the centers of Monte Gibele, Cuddia di Mida and Montagna Grande. Characteristic of the area are the "favare," jets of water vapor that can reach as high as 100°C and flow out of cracks in the rock intermittently, accompanied sometimes by the emission of sulfur dioxide and hydrogen sulfide.
The main one of these is Favara Grande, which is located on the slopes of Montagna Grande. Hydrothermal manifestations, on the other hand, are mainly located along the coast in the central-northern portion of the island and are characterized by temperatures around 50°C. Currently, the main risk is the release of toxic gases - CO, CO2, H2S, SO2 - rising from fractures in the soil. In particular, carbon dioxide, which is denser than air, in the absence of wind tends to accumulate at ground level where it can reach very high concentrations, and being colorless, odorless and tasteless is difficult to detect. At low concentrations it can cause increased respiratory activity, nausea, visual disturbances and for high concentrations asphyxiation.
The facilities in charge of monitoring volcanic activity on the island of Pantelleria are the Catania and Palermo sections of the National Institute of Geophysics and Volcanology (INGV).
The network consists of seismicity and ground deformation monitoring systems. Periodic water and gas measurements and sampling are also carried out.